As is usually the case, one of these articles comes about after someone asks my opinion regarding one of our servos. This time regards using a DS630BLHV for steering a Traxxas Sledge. And not just one guy, but two this very morning (and maybe 15-20 over the last few weeks since its release). Then another guy wrote saying he'd not even ordered the Sledge yet, so he didn't even have it yet but wanted 'our' steering servo recommendation.
TL;DR . . . the short answer. To the first guys, no, we don't recommend the DS630 (a Series 1 servo) . . . get the DS635 (a Series 2 servo), instead. And for the third guy, the newbie still buying, same thing, get a DS635 for that rig. Pretty big and fast, really needs a strong servo! For the more nuanced answer, read on . . .
Q1. I've heavily modified my Traxxas Sledge and am wondering if
the DS630BLHv is a good choice. Also, I've heard it won't work when
plugged into the receiver, so I'm confused about this, and what's the
warranty for this servo?
Q2. I am running a heavily modded Traxxas sledge and
was wondering can I plug the DS505BLHV straight into receiver and use it? I've seen something about you recommending a separate battery so what's the real story? Also, I originally bought a servo off Amazon and couldn't get warranty help when I tore it up so is
there any warranty for ProModeler products? Thank you.
Q3. I'm buying a Sledge but don't have it yet. I'm a bit confused and overwhelmed with upgrades I'm ordering. What servo should I get and what other items would
I need?
There are actually 4 questions within these three queries;
- Is a DS505 or DS630BLHV a good choice for a Sledge? No.
- Does it work when connected straight to receiver? Yes, but . . .
- What's the warranty? 1-year
- Which servo do you recommend for a Traxxas Sledge? Series 2 . . . DS635/845/1155
A. Is a DS505 or DS630 a good choice? Since the only difference is the motor (otherwise, they're the same servo), I'll answer for both with . . . nope, not a good choice. Not for such a fast and heavy rig as the 1/8th scale Traxxas
Sledge (sorry if it's not what you want to gear, but you did ask).
Why not? Honestly? I wouldn't recommend any of our series 1 brushless
servos for the job (DS505, DS630, and DS930). Maybe the DS930, but not really because they al share the conventional 25T output shaft. We're using the best steel there is and you can twist it upon impact too easily in our opinion. The rig needs a more heavily built servo..
Eyeball this photo of a DS930 shaft damaged by a heavy rig. It's been twisted because of the external forces of hitting a stump or a curb (most likely). And we've seen them snapped in two!
- This is a steel output shaft of a DS930 twisted like a pretzel by an impact
Here's a photo of our original DS635 and the V2. Other than larger
output shaft plus a larger bearing, they're the same. Take note the
ginormous difference in the size of the spline. It's massive. In fact,
it's what we use for our quarter scale servos outputting +2000oz-in
Our series 2 servos (DS635, DS845, and DS1155) use the large spline.
- The larger shaft of the DS635 version 2 in the foreground
But there is also gear size involved in the decision. So let's frame this a bit better with another photo. This next one shows the relative size of DS505/630 output shaft on the left (remember they share the same gear train, just a different motor), our DS930 output gear in the middle, plus that of the 25T version output spline of an original DS635 on the right (since this photo we switched to ø8 instead of the original ø6). So inside, the 930 gears are larger than the 505/630, but the 635 are even larger than the 930 and the output shaft is also more gnarly.
- ProTip: the output gear is the biggest gear in the servo because it deals with the brunt.
- DS505/630 on left, DS930 middle, DS635 right
Background
So the output gear of the DS635 is thickest, next is the DS930 gear, then the DS505/630 which incidentally, has about the same size output gear as a Savox 2290SG. Don't mistake the DS505/630 gears for weak, just not our strongest. Please don't misunderstand what we're saying!
Summarizing, it's my opinion, the right servo for the Sledge is going to see
you stepping into a Series 2 servo instead of one of our Series 1. However, no matter what 'I' think, you're the customer - so you're always right - and if you want to use a DS505 or DS630 because you don't think you're going to stress it very hard, then KYO because you're a big boy. E.g. do as you please. But since I'm being asked my opinion, then you're getting my unfiltered thoughts, capisci?
- I'm telling you, don't buy a DS505 or DS630 for a Sledge, get a Series 2 servo, instead.
ProTip - while we offer three Series 1 servos and three Series 2 servos (DS505/630/930 versus DS635/845/1155), and while all six are about the same physical size (meaning a standard class 20x40 footprint servo with conventional mounting beams), and while they have all-steel gears, the series I servos are far more suited for crawling versus bashing because of the 15T output shaft (the 25T is the same as Futaba, Savox, et al).
So for bashing, you're going to be way ahead of the
game by opting for the significantly more heavy duty drive train of our
Series 2 servos. Eyeball the next picture to see how they're built inside (photos of a type competing products never show you).
- Note the massive shafts and heavy reinforcements
What do you see? Not just big ass gears and larger diameter steel shafts, but the alloy case is heavily reinforced. Basically, you're getting better parts
from which to begin your adventure with a Sledge, OK? Anyway, better parts make for better
servos, agreed?
Basically, we try to earn your business the old
fashioned way . . . more bang for your buck!
DS635 or DS845 or DS1155?
OK, so we recommend a Series 2 servo instead of any of our Series 1, which one is best? Short and sweet . . . it's our experience our DS635BLHV is well suited for largely stock Sledge just because it's more heavy duty. So if the servo is destined for a heavily modded rig, meaning heavier, then we advise you opt for either our DS845BLHV, or DS1155BLHV (just for the added grunt required when turning big heavy tires at high speeds).
The more nuanced reasons why . . . it's because more power is required as weight and speeds go up. Means it takes more grunt from the servo.
Look, in offering up 22 volts of oomph, Traxxas put in your hands
something which will hurtle into the 70s speed-wise! To put this into
context, 70mph is about 100fps (feet per second). Since the average house is
about 100 feet long, it means this thing is hurtling along pretty quick at top speed . . . it's über fast (a technical term for lickity-split)
Your Sledge carries a lot of beef. And a modified version (with bits and bobs made of alloy and steel) weighs even more!
Why heavy and fast - together - matters!
Why? Simple, let's turn to Newton's law of Motion (there are three). The 2nd and 3rd are germane to the Sledge discussion. The
2nd states that the force on an object is equal to its mass times
its acceleration. Written it looks like this; f=ma*a . . . if the mass is the same (same rig no matter how fast), as you're going faster and faster (definition of acceleration), then the faster you go the harder you hit the fence post, or plant it after a 100' jump. Means ultimately, something's gotta give! So that's 2nd law.
Meanwhile, the 3rd law states there's an
equal and opposite reaction for every action. So if your rig just kisses a curb at 70mph then it's the same as if it were standing still and the curb came out of nowhere and hits your Sledge - at 70mph - it's the exact same exact thing, either way.
Put 2nd and 3rd together and it means the force being generated - maybe just cutting
the wheels at a bit of speed - can be enough to overwhelm the gear train and spline of a conventional
servo. Conventional being our Series 1 servos (as well as competing designs like Savox 2290SG, MKS HBL599, or Futaba CB700). Why? Just because a lot of mass at speed is harder to steer because it imposes higher forces!
This next photo shows the comparison of the Savox 2290SG gear train to that of the DS635 and take note of the relative size of the final drive, the output gear, the largest within the servo. This is an example of how bigger is better. Our series II servos are beefier inside and just more durable.
- 2290SG gears juxtaposed with DS635BLHV gears
Continuing with comparison to the Savox 2290SG (a good servo, we're not saying otherwise), this time juxtaposed with the DS630 (instead of the DS635 we recommend),
and which to remind you, differs in the motor only from the DS505, note the
construction . . . one is reinforced, the other puts the steel gear shaft
directly in the aluminum.
Steel, bronze, and aluminum - of course - are metals, but the bronze is second only to steel with regard to hardness within our servos (and both are FAR stronger and harder than aluminum). So putting a harder metal (steel or bronze) in place (an insert) to shield the soft aluminum is called metal reinforcing. So we use bronze (and sometimes, steel, or even bearings) when reinforcing our aluminum alloy servo cases where shafts fit in the highest impact location. In fact, we're unique in the industry in bronze reinforcing even our entry level $29.99 servos!
Which is best? Honestly, any of them are way better than the big fat nothing you find inside more cheaply manufactured products (to include the no-names on Amazon) plus a host of servos available by online hobby shops (ones who instead of handling quality brand name products seek a low cost manufacturer in Asia to produce their private label offerings). And note, since we buy competing servos and
no-names to inspect for what we may learn, we weren't surprised to
discover the hobby shop brands are actually made pretty much exactly
like the el cheapo no-name products (and in one instance we know with certainty, by the very same Asian manufacturer).
Anyway, to the question
of, is a servo better if it's made with reinforcements, or would you rather have
a servo where the steel shafts are fitted directly into soft aluminum?
We think the answer is a no-brainer but it's really up to you to decide, not us. Point being, when shopping, just because it's shiny and pretty on the outside doesn't mean jack!
Why the larger spline shaft and bearing?
Because all else
being equal, when it comes to trucks, bigger is better . . . and yes, we
have a Sledge horn available to suit. Part number PDRS16F-15T. Click the link and it'll open a separate browser tab so you don't loose your place.
- This is a marvelous steering combo for your Traxxas Sledge
Recapping:
So we went bigger with the internal components expressly with the series II in order to handle the forces being imposed by faster and bigger rigs. Recall, Traxxas set about standing the 1/8th scale off-road world on its head with the Sledge. How? By redefining the entirety of the concept through their engineer's bag of tricks.
Tricks? Yes, because the Sledge is a monstrous rig operated at seriously fast speeds on high voltage. Honestly, just making it and bringing it to market (from 'this' product designer's perspective), has been quite an impressive trick in the first place! So trick is the right word in many regards. If nothing else, it's quite a trick rig all in and of itself, too.
Why doesn't Traxxas equip the Sledge with a better servo?
I alluded to it above. Successfully bringing it to market involves a host of compromises. Some will buy it for a 9 y/o who will dink around in the back yard until they break it and return to their Nintendo Switch, the Sledge forgotten. So if Traxxas used the best of everything it would cost $2000 and nobody but aficionados would buy it - and certainly not many Moms for their little kid!
So the major difference between you and Traxxas when selecting the steering servo is they have to factor cost above pretty much everything in order to broaden the market to include everybody. Nice thing is this means you can belly up to the counter and plunk down the MasterCard to bring together your vision of the perfect rig, but they have to contend with bringing the whole thing to market . . . at a price for which folks will step up to the plate and whip out the MasterCard!
Enter our Series II servos, which is what we unequivocally recommend for the Traxxas Sledge. But let's laser in on the answer to the actual question (unasked), what's enough torque and why?
- Stock rig, light upgrades - DS635BLHV
- Modded rig, quite a few upgrades and bigger tires - DS845BLHV
- Heavily modded rig, best of the best, fast and heavy as they come - DS1155BLHV
Let's close with regards to plugging it in to your receiver and will it work? Yes it'll work;
-
But you're asking the wrong question.
Right question is, will it make rated power when connected to a receiver and powered by the typical hobby grade ESC with a BEC circuit? Nope, I don't think so, but you're free to do as you please because as we said earlier, you're the customer and thus, you're always right.
So if it were me, then instead of relying on a free BEC that came with the ESC,or even an aftermarket one because analog juice beats digital no matter what, then I'd run a dedicated pack like a B2S850 - or - pony up for a good quality stand alone BEC (if you insist on synthetic juice).
ProTip: while I recommend an 850mAh pack, our packs sizes range from 650-6000mAh, and the 850 is probably about right in my estimation (good for maybe 3 runs between charges), but if you can fit the 1500, then it'll run for about twice as long on a charge (call it every 6th time you charge the propulsion pack). Are we the only ones steering you away from using BECs with performance models? Nope, so does Futaba.
ProTip: our packs (and suggested BEC) come with 2 power leads to the receiver instead of 1. This is because otherwise, you can't comfortably get more than 5A into the receiver.
Eyeball the servo specs. Specifically, look at current draw while stalled (meaning when it's making rated power) and then you'll understand why single-lead 'solutions' are really anything but. One lead is a 5A connection to the receiver so a typical BEC backfeeding the the ESC into the receiver through the throttle channel lead limits you to 5A and begins overheating at the 3.5A the connector is rated for. So using two leads, one to the receiver at BAT and the orher connected to the receiver through an unused channel, maybe channel 4, gives 7A before beginning to overheat, a practical 10A in the real world.
A real world problem is the specs for a BEC don't mean what you think. I'm saying you can't take what marketing says as gospel because they lie. Especially companies selling inexpensive consumer grade goods imported from Asia (or even assembled in USA of imported components).
So like you read servo specs (and a Savox 2290SG, incidentally, makes rated torque at 8.3A), then you also have to read the specs of BECs, also. And if read the specs of products by the best companies, you learn 20A BECs aren't really 20A. More like 7-8 at the voltages we're concerned with. Yup, output current totally depends on voltage input. Also depends on temperature because they rate them at 77°F with a 10fps cooling breeze. Cooling breeze, under the plastic shell of a rig? Hah! Anyway, they rate them for lab conditions. You're not getting what you think and no matter what, they put out digital juice versus analog.
- BEC versus battery is like the difference between Tang and real orange juice!
That said . . . and in fairness . . . while we believe you should use a separate battery to power it, you're the customer and may instead decide to wait and see. Wait for what? Until after you run it a while.
So how do you decide?
Basically, if you want more power from the servo (you'll know), then you can order the battery
and harness we offer for Traxxas owners (they're a 6V system so the
harness splits power so only the servo gets 8V and thus, protects the
radio from going poof).
Major point being, some folks are happy enough
with the power they get from the servo using the built-in BEC, so if
you're one of them, then you don't need a dedicated battery! By the way,
I'd share the same advice with you regarding any servo making 500+
oz-in as this is a matter of physics, not opinion so if you decide a
Savox 2290SG suits you better, I advise you treat it similarly.
Finally, the Sledge has motor clamps with a pair of threaded holes in
each which makes for a great place to mount a bit of flat stock material
for battery mounting. Speaking of mounting, I like using 3M brand Dual
Lock Velcro TB4575, which I buy off Amazon to hold it in place.
Finally, if you're curious, these articles touch on why we believe a dedicated pack's better. And like I've said, we'd say the same if you're running a Savox 2290SG, MKS HBL55, or Futaba CB700, or anything else making +500oz-in, then please believe me, a standalone battery is a better power supply for your control electronics than any BEC on the planet.
Warranty?
1-year parts and labor against manufacturing defects and workmanship.
Does this mean you can't break it? Hell no! Why not? Because we're not stupid, modelers can break anything! This includes even our Series 2 with the gnarly gears and massive 15T output shaft.
Anyway, good luck in whatever you decide but please trust my guiding you to a Series 2 steering servo versus one of our Series 1 or any competing servo using a 25T spline because as the designer, I know what our servos can take (and that Sledge is no joke, and definitely not a toy).
SummaryFor a Sledge I'd use a
DS635 and the
factory BEC system (means just plug it in where the old servo was
and it works). For a heavily modified one (lots of heavy aluminum aftermarket parts, big motor tires, etc.) then I'd use a DS845 or DS1155. Depends. Your call. So our series 2 are the best we have. However, at just $100, you can also use
a Series 1
DS505BLHV or even a DS930, instead.
But I don't advise the Series 1 servos because the more burly Series
2 servos exist for good reason.
And review my thoughts for why opting on
a
$60 Amazon special isn't such a great deal. Ditto the hobby
shop labeled imports because they're the same kind of thing (but
with some hobby shop's whiz bang label engineering). Those compared
to ProModeler, Futaba, MKS, Savox, et al. Trust me, I make these
things and I know more than you - it's the same advice I'd give a
nephew.
Of course, you're a big boy, so it's your decision. Anyway,
whichever servo you decide is best for you, if it's ProModeler,
you're going to like it. Ours are better built and more durable than
the imports. There's a 1 year warranty,
visit the page for the details.
Last thing; if you just plug it into the receiver and go drive the
rig, it'll work. And yes you'll be happy - but - I predict one day
you'll wish the steering were more crisp at higher speed. You'll
want the rig to cut harder/better/sharper and that's when power
decisions your make before installing the servo will affect the
solution.
If you're using a dedicated battery, the solution will be a stronger
servo. But if the servo is running on a BEC, then fixing problem of
it not being crisp won't necessarily mean you need a new/stronger
servo. Instead, it more likely means you'll need to upgrade how you
power the servo (true for any 500+ oz-in servo regardless of brand).
I say this because physics affect all servos equally. Nobody makes a
magic 500-1000oz-in servo that uses half the amperage of someone
else's, OK?
Fundamental reason will be the Traxxas servo-power supply (BEC circuit of
an ESC is called a BEC for battery eliminator circuit). Anyway, it
isn't really up to handling a high performance servo (which you'd
expect since they're intent on building it as cheaply as possible so it sells better).
So the upgrade involves two power alternatives, an
aftermarket BEC
or a
dedicated battery.
Or you can spend a lot of money on a new motor and ESC which has a
better BEC (and maybe it's good enough, maybe). Anyway, we have both, just
click these links to learn about them before ordering your servo.
Note; reason we don't recommend upgrading the stock Traxxas motor and ESC is
they're actually pretty decent. So I wouldn't do that until they
wear out, but it's your money.
Speaking of which, if you ask around on FaceBook, I predict 9 out of
10 say they use a BEC to power their system. But I also bet they've
upgraded motors and maybe use an aftermarket ESC like Hobbywing, or
similar. Lot of money, and remember, some of those aren't up to the job,
either because hairy ass servos consume lots of power (amperage, not voltage).
Me? I'm an old engineer and thus, I know of no BEC that compares favorably to
a battery. They're just not good enough. So for my models, I'll take
the quality of a battery over a BEC any day of the week. And I advise, until you
know more about this than me, you should also run a receiver battery, which incidentally is exactly what all the expensive gasser-powered rigs use.